In this chapter the anatomy and shapes of root canals of all the teeth like incisors, canines, premolars, molars along with possible variations both in mandibular and maxillary teeth is well described in a compact, easy to understand and remember table-form covering under the headings, which tooth, number of roots present, size of tooth, accessory roots, apical 1/3rd of the root, position of apical foramen, special remarks. The root canals, its variations, are well covered with the help of 84 figures of original cut human teeth in both longitudinal and cross sections for complete and crystal clear understanding in the mind of the reader, because the “procedure of RCT” (Preparation/ instrumentation of the root canal) mainly depends upon the shape and anatomy of the tooth to be RCTed.